As an example of a liquid ejecting apparatus, an ink-jet type printer apparatus including a liquid ejecting head for ejecting a liquid (an ink) through a nozzle hole onto a recording target material has been known. The liquid ejecting head equipped in the printer apparatus includes a flow passage unit in which a plurality of channels each connecting a pressure chamber and a nozzle hole to each other are formed; and an actuator for applying an ejecting pressure to an ink contained in the pressure chamber. The liquid ejecting head distributes an ink supplied from a tank to a plurality of pressure chambers and applies a pulsed pressure to one or a plurality of pressure chambers out of all the pressure chambers. Thus, the liquid is ejected through a nozzle hole linked with each pressure chamber to which the pressure has been applied, so that the ejected liquid may be adhered onto a recording target material for forming an image thereon. At this point, an example of the actuator used for applying a pressure to an ink contained in a pressure chamber is a piezoelectric actuator, and a drive circuit is provided for driving the piezoelectric actuator.
For example, as described in Japanese Patent Application Laid-Open No. 2007-196404, the drive circuit is provided on a flexible board, a ground line and a high potential line corresponding to input lines to the drive circuit are formed on the flexible board, and a plurality of signal lines for inputting control signals for operating the drive circuit are also formed thereon. Such a flexible board is connected to the piezoelectric actuator, and the drive circuit and the piezoelectric actuator are connected to each other through a plurality of driving voltage lines through which voltages selectively output from the drive circuit are input to respective individual electrodes of the piezoelectric actuator. Furthermore, another ground line is formed on the flexible board in order to apply a ground voltage to a common electrode of the piezoelectric actuator.
In such a piezoelectric actuator, when an individual electrode is biased toward a high potential by a driving potential selectively output from the drive circuit, a predetermined electric field is generated between the common electrode biased toward a low potential through the ground line and the individual electrode. Due to the generated electric field, an active portion of a piezoelectric layer disposed between these electrodes is deformed, and hence, a pressure is applied to an ink contained in the pressure chamber so as to eject the ink from a nozzle hole.
It is noted that a larger number of lines are provided between a drive circuit and a piezoelectric actuator so as to reduce a line pitch in accordance with increase of channels, and hence, inexpensive general purpose products such as an FFC (Flexible Flat Cable) cannot be used as a flexible board connected to a piezoelectric actuator, and therefore, it is necessary to use a flexible board according to the specifications of a piezoelectric actuator. Moreover, a COF (Chip On Film) on which lines are formed as desired and a drive circuit is mounted may be used, and thus, a flexible board to be used tends to be expensive. Therefore, Japanese Patent Application Laid-Open No. 2007-196404 discloses a structure in which a flexible board is divided into two parts, that is, a COF on which a drive circuit is mounted and which is connected to a piezoelectric actuator and a general purpose FPC (Flexible Printed Circuit) extending from the COF toward a main body of a printer apparatus, and thus, an expensive COF is employed in a necessary region alone.